Characterization of magnetic resonance (MR) findings of malignant and benign vertebral compression fractures

Abstract

Introduction : Differentiation between benign and malignant causes of a vertebral compression fracture is a common clinical problem, particularly in elderly patients. Establishing the correct diagnosis is of great importance in determining its treatment and prognosis.

Objective : To examine and characterize MR findings of malignant and benign vertebral compression fractures.

Setting : BMA General Hospital

Research design : A retrospective study

Patients : Patients with MRI of thoraco-lumbar vertebral compression fractures from December 2007 to December 2008 were recruited into the study.

Methods : The data collected for examination were MRI conventional T1W, T2W echo sequences in the sagittal and axial orientations with 5mm thickness. Vertebral compression fractures were examined for abnormal bone marrow signal intensity, convex of posterior cortex, retropulsed bony fragment, signal intensity and enhancement of adjacent discs, involvement of posterior elements, presence or absence of paravertebralepidural mass, endplate integrity and fluid sign in fracture endplate. The diagnoses were confirmed by surgical findings, follow up MR imaging, clinical follow ups, or unequivocal imaging findings.

Results : Twenty-five malignant vertebral compression fractures (25 metastatic carcinoma) and 59 benign ones (21 osteoporosis, 4 post-trauma and Conclusion 34 spondylitis) were identified. The features of metastatic vertebral compressions were abnormal bone marrow signal intensity (100.0%), convexity of posterior cortex (80.0%), involvement of the posterior elements and pedicles (68.0%) and epidural/paravertebral soft-tissue mass (52%). Spondylitis compression fracture showed abnormal bone marrow signal intensity (100.0%), epidural/paravertebral soft-tissue mass/abscess (88.2%), abnormal endplate disruption (67.6%), high T2 signal intensity and increased enhancement of intervertebral discs (61.8%,61.8%) and posterior elements involvement (58.8%). MR features of acute osteoporotic fracture were abnormal marrow signal intensity (75%), complete preservation of vertebral signal intensity (25%), retropulsed bony fragment (66.7%) and fluid sign beneath the fractured endplate (66.7%).

Conclusion : Convexity of the posterior vertebral cortex was determined to be Keywords suggestive of, but not specific for, a malignant origin. Three good to excellent features, considered typical for spinal infection are, namely: endplate disruption, high T2 signal intensity and increased enhancement of intervertebral discs. At least two adjacent vertebral lesions are also more typical for spondylitis than neoplasm. Preservation of signal intensity of the vertebra is suggestive of the benign nature of a collapse. A retropulsed bony fragment and fluid sign beneath a fractured endplate were considered typical for acute osteoporotic vertebral compression fracture. Age and sex were not useful in differentiating of malignant from benign vertebral compression fractures. MR imaging is therefore helpful in distinguishing a benign from malignant vertebral collapses. However, when MRI features are atypical or equivocal, correlation with other imaging techniques, a short internal follow-up of MRI examination and biopsy, may be needed to establish a correct diagnosis.